1. It is + adj. + that sb. (should) do
常见的形容词有：necessary, important, strange, natural
It's important that he take my advice.
2. It is + n. + that sb. (should) do
常见的名词有：a pity, a shame, no wonder, one's wish
It's a pity that he be so silly.
3. It is + done + that sb. (should) do
常见的过去分词有：suggested, advised, demanded, requested, required, asked, ordered,
proposed, decided, desired, insisted等。
It's requested that she go home as soon as possible.
1. 表命令，表建议，表要求的动词，后接宾语从句虚拟。虚拟的构成为(should) do。
I advise that he stay at home.
I wish I had watched the football match last night.
1. as if, as though
He speaks English as if he were a native speaker.
2. otherwise, but, even though
He was ill. Otherwise he would have been there.
3. with, without, but for
Without your help, I would have died two years ago.
But for your help, I would have died two years ago.
4. would rather I'd rather you told me yourself.
5. It's time that
It's time that you went to bed.
It's time that you should go to bed.
在表语从句中，表示间接的命令，要求、请求、建议、决定等，主句中的主语通常是suggestion, proposal, request, orders, idea等。从句谓语形式是"(should)+动词原形"。如：
His suggestion is that we (should) leave at once.
Peter is a good student except that he is sometimes careless.
That he ever did such a thing I don’t believe.
She said that, if she failed, she would try again.
He told me that if it was necessary they would work extra time.
We should consider the students’request that the school library provide more books on
popular science. (that引导同位语从句)
The only hope that he expressed was that they would do what they could to help the people
in disaster areas. (that引导定语从句)
What is known to us all is that the 2008 Olympic Games took place in Beijing.
It is known to us all that the 2008 Olympic Games took place in Beijing.
本句含有一个主语从句，主句的动词为is known to。
As is known to us all, the 2008 Olympic Games took place in Beijing.
关系代词有who, whom, whose, which, that, as,和关系副词when, where, why。
a. 先行词有all, everything等不定代词时，如，
Everything (that) he did is wrong.
b. 先行词被all, every, no, some, any, little, much等修饰时，如，
I'll read all the books (that) you lend me.
This is the first letter (that) the boy has written.
d. 先行词被the only, the very, the same, the last修饰时，如
He is the very man (that) I'm looking for.
This is the book about which we have talked a lot.
The book, which he gave me yesterday, is very interesting.
This is the room where I worked.
This is the room which I stayed in.
I remembered the day when we lived there.
I remembered the day that I spent there.
as 可以放于句首，而which 不可以
As you know, he is good at English.
three of them 和three of which
I have a lot of books, three of which are in Russian.
I have a lot of books and three of them are in Russian.
(3. )先行词在从句中充当地点状语时，关系词用where 或者介词加which;先行词在从句中充当时间状语时，关系词用when或者介词加which;先行词在从句中充当原因状语时，关系词用why或者for which。
2. no matter wh- 与wh-ever 的联系及区别：no matter wh- 只引导让步状语从句，此时与wh-ever通用。wh-ever又可引导名词性从句，No matter wh-不能。
No matter when / Whenever he comes back, he should be invited to the party.
4. 状语从句的倒装一般有下面几种情况：①否定词开头;②so 加adj. 开头;③as /
We had sailed four days before we saw land. (……才)
We hadn’t run a mile before he felt tired. (不到……就)
Please write it down before you forget it. (趁……)
Before I could get in a word, he had measured me. (还没来得及)
It will be/was…before…要过多久才……
6. because, since, as 引导原因从句的区别：because表达直接原因，语气最强，回答why;
8. till, until和not…until的区别;if和unless的区别。
1.下列动词或动词短语后接不定式：agree, seem, appear, offer, happen, wish, hope, pay,
expect, long, plan, intend, promise, pretend, decide, afford, manage, choose, be said to,
would like to等。
2. 不定式常用的句型：too…to do (太……而不能), …enough to do…(够……就能
……), so as to do/in order to do(为了……)，so…as to do/such…as to do(如
否定结构为“not (never) to do”;疑问结构是特殊疑问词“how (what, which, who, whether…) to do”;复合结构是“for/ of +名词(或代词宾格)+ to do ”。
4. let/ make/ have/ see/ hear/ notice/ observe/ listen to/ look at/ watch/feel
5. 当前面是the first, the second, the last, need, plan, time, chance, right, determination,
6. but/ except + to do/ do 结构，要根据谓语动词来确定其后面的形式。当谓语动词是do,
does, did时，but后用动词原形;谓语动词是其他动词时，but后用“to + 动词原形”的形式。
7. 形容词后一般用不定式(除busy, worth 两个外)。
You are sure to succeed. 你一定能成功。
He is busy preparing his lessons at present. 他现在正忙于预习功课。
This is a bench to sit on.(这是用来坐的凳子。)
This room is comfortable to live in. (这个房间住起来很舒适。)
The question is easy to answer. (question是answer的宾语，不能说：The question is easy to be answered. 也不能说：The question is easy to answer it .)